论文标题
可压缩的湍流通道流中的大规模动作和自相似结构
Large-scale motions and self-similar structures in compressible turbulent channel flows
论文作者
论文摘要
在这项工作中，我们研究亚音速和超音速湍流中对数和外部区域运动和结构的规模特征。为此，进行了一系列对中等雷诺数下的可压缩湍流通道流的直接数值模拟。基于此数据库，通过两点相关和一维光谱研究了外部区域运动的流向和跨度长度尺度。发现外部区域的多尺度结构之间的能量分布是由半局部摩擦 - reynolds-number效应而不是马赫特格效应所支配的。该结论不仅适用于速度波动，而且还具有热力学变量的波动。此外，当流动通过先前的实验研究报告时，外运动的流向和跨度长度尺度不会显着改变（Bross等人，J。FluidMech。，第911，2021卷，第2021卷，A2）。另一方面，通过采用线性相干频谱研究了填充对数区域的自相似结构。流向速度和温度波动的自相似壁连接结构的流向/壁正常比率约为15.5，密度和压力波动的对应物为1.8。本研究证实了可压缩壁湍流中的自相似结构的存在，并评估其几何特征。
In this work, we study the scale characteristics of the log- and outer-region motions and structures in subsonic and supersonic turbulence. To this end, a series of direct numerical simulations of the compressible turbulent channel flow at medium Reynolds numbers are performed. Based on this database, the streamwise and spanwise length scales of the outer-region motions are investigated by the two-point correlations and the one-dimensional spectra. The energy distribution among the multi-scale structures in the outer region is found to be dominated by the semilocal friction-Reynolds-number effects rather than the Mach-number effects. This conclusion not only holds for the velocity fluctuations but also the fluctuations of the thermodynamic variables. Besides, the streamwise and spanwise length scales of the outer motions do not alter significantly when the flow passes the sound barrier as reported by a previous experimental study (Bross et al., J. Fluid Mech., vol. 911, 2021, A2). On the other hand, the self-similar structures populating the logarithmic region are investigated by adopting a linear coherence spectrum. The streamwise/wall-normal aspect ratio of the self-similar wall-attached structures of the streamwise velocity and temperature fluctuations is approximately 15.5, and the counterpart of density and pressure fluctuations is 1.8. The present study confirms the existence of self-similar structures in compressible wall turbulence and assesses their geometrical characteristics.
